In association with miniaturization and enhanced performance of electronic products including LSI chips, there has been strong demand for a reduction in package size and high density packaging. Under these circumstances, various package structures have been proposed. Particularly, in recent years, there have been proposed a double face package (hereafter abbreviated to DFP) for stacking LSIs in order to increase packaging density, and an IC built-in substrate including an IC or LSI disposed within the substrate. The DFP and the IC built-in substrate require a structure which includes vertical interconnects for establishing electrical connection between an LSI-chip mounted substrate and electrodes on the side opposite the substrate or establishing electrical connection between the LSI-chip mounted substrate and an upper substrate, and/or horizontal interconnects for wiring. In general, vertical interconnects of a DFP are formed through employment of a structure in which vertical interconnects are previously formed in a substrate, a method of forming openings in resin after performance of resin sealing and filling the openings with plating, or a structure in which electrodes extend through a silicon substrate such that the electrodes are exposed on opposite faces thereof. As described above, the structure according to the conventional technique is likely to increase cost, because a complicated process is required for formation of vertical wiring and rewiring.
Patent Document 1 discloses the structure of an IC built-in substrate using an organic substrate. In this IC built-in substrate, solder balls or metal post structures are used as vertical interconnects. Since a thick metal player which corresponds to a support layer is provided on upper and lower substrates in the manufacturing process, the manufacturing process requires a step of removing the thick metal layer after the upper and lower substrates are joined together. Therefore, the manufacturing process is complex, which greatly increases the production cost.
Patent Document 2 discloses an electronic component for interconnection which solves the above-mentioned problem. In the electronic component for interconnection, additional processes for forming vertical wiring and rewiring, which are required for formation of the structure of a double face package (DFP) or a wafer level chip size package (hereinafter abbreviated to WLCSP), are implemented through use of a component for vertical wiring and/or rewiring, to thereby simplify the manufacturing process. FIGS. 40(A) and 40(B) show a side sectional view and a perspective view of the electronic component for interconnection disclosed in Patent Document 2. This electronic component for interconnection is formed through electroforming such that a plurality of vertical interconnects and horizontal interconnects connected thereto are integrally connected by a support plate formed of an electrically conductive material. Since the electronic component for interconnection is formed through electroforming, after the electronic component for interconnection is incorporated into an electronic device package, the support plate can be easily separated from the wiring portion, such as the horizontal interconnects and the vertical interconnects, through application of heat and/or pressure. Thus, the plurality of vertical interconnects and the horizontal interconnects are connected at predetermined positions.
In general, a semiconductor manufacturing process is divided into a former stage for fabricating an LSI and a latter stage for packaging the LSI. There are a few manufacturers that specialize in the latter stage but can cover the former stage. Manufacture of conventional electronic device packages, such as wafer level chip size package (WLCSP), requires a process of performing rewiring, vertical wiring plating, etc. on a wafer; that is, requires facilities similar to those used in the former stage, and cannot be performed by use of only conventional facilities for the latter stage. However, through employment of an electronic component for interconnection as disclosed in Patent Document 2, the production cost can be reduced by entrusting the production of the component to a dedicated manufacturer. In the case of WLCSP or the like, through replacement of the vertical wiring and/or rewiring forming processes with a component, it becomes possible to put together off line, in the form of a component, processes which require facilities similar to those used in the former stage, to thereby enable manufacturers dedicated for the latter stage to enter into manufacture of such packages without large investment. However, the electronic component for interconnection as disclosed in Patent Document 2 requires a high-cost process such as electroforming or plating. Also, in the case where electroforming is employed, a dedicated apparatus is required to separate a support plate, which results in an increase in the number of steps and cost.